* WHAT. The Minnesota Pollution Control Agency has issued an Air Quality Alert for fine particles pollution. The Air Quality Index (AQI) is expected to reach the Purple or Very Unhealthy category. * WHERE. North central, northeast, and northwest Minnesota. * WHEN. 1 PM CDT Saturday until 9 AM CDT Monday. * IMPACTS. The risk of health effects is increased for everyone. * ADDITIONAL DETAILS. Heavy surface smoke from Canadian wildfires will drift south into Minnesota over the next several days. This smoke will initially impact far northern Minnesota early Saturday afternoon and then spread south and east through the rest of the day and into the evening. Smoke lingers across the region on Sunday with light winds in place, and then exits back to the north through Monday morning. The highest smoke concentrations are expected to be across far northern Minnesota and the Arrowhead region from Saturday into Sunday.